Effects of fineness and substitution rate of GGBFS on material characteristics of GGBFS-blended cement mortars: Hydration, non-evaporable water, pore structure, mechanical properties, self-desiccation, and autogenous shrinkage

초록

This study aims to evaluate the effects of the substitution rate and fineness of ground-granulated-blast-furnace slag (GGBFS) on microstructure formation and autogenous shrinkage in order to improve the usability of GGBFS-blended cementitious materials at construction sites. Specimens were prepared using different GGBFS substitution rates (0, 50, 65, and 80 %) and fineness values (4330 and 7650 cm2/g). The hydration kinetics, non-evaporable water content, pore structure, compressive strength, internal relative humidity, and autogenous shrinkage of each specimen were measured. The experimental results showed that self-desiccation and autogenous shrinkage increased as the GGBFS content increased in specimens with up to 65 % GGBFS substitution rate. This is because GGBFS reduces the volume fraction of capillary pores and increases the capillary stress, although it delays the hydration reaction at an early age. The self-desiccation and autogenous shrinkage decreased in the specimens with an 80 % GGBFS substitution rate because the amount of cement was too small; thus, the hydration reaction of the binder was insufficient. Moreover, adding GGBFS with high fineness increased self-desiccation and autogenous shrinkage owing to the GGBFS particles acting as nucleation sites and inert fillers. © 2024 Elsevier Ltd

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